Method of preparing a toner dispenser

ABSTRACT

A TONER DISPENSER IS DISCLOSED FOR USE IN AN ELECTROSTATIC PRINTING APPARATUS. THE DISPENSER MEMBER COMPRISES A SUPPORT SHAFT, A POROUS DISPENSER ROLL AND AN INTERMEDIATE POLYMERIC ADHESIVE.

June 19, 1973 e. c. BHAGAT METHOD OF PREPARING A TONER DISPENSER 2Sheets-Sheet 1 Filed June 11. 1971 INVENTOR OPAL C. BHAGAT ATTORNEY G.c. BHAGAT METHOD OF PREPARING A TONER DISPENSER June 19, 1973 2Sheets-Sheet 2 Filed June 11, 1971 United States Patent 3,740,288 METHODOF PREPARING A TONER DISPENSER Gopel C. Bhagat, Rochester, N.Y.,assignor to Xerox Corporation, Stamford, Conn. Filed June 11, 1971, Ser.No. 152,135 Int. Cl. B29c 19/06, 19/00 US. Cl. 156-275 11 ClaimsABSTRACT OF THE DISCLOSURE A toner dispenser is disclosed for use in anelectrostatic printing apparatus. The dispenser member comprises asupport shaft, a porous dispenser roll and an interme diate polymericadhesive.

BACKGROUND OF THE INVENTION This invention relates to a dispensingapparatus and more particularly to a dispenser of toner particles in anelectrostatic printing apparatus.

Generally, toner dispensers for electrostatic printing machines comprisea hopper having an opening at the bottom thereof for the gravity feed oftoner particles into some portion of a developing apparatus locatedbelow the opening. Actual dispensing of the toner particles isaccomplished by the use of a metering device supported across theopening and arranged to be activated to an open condition periodicallyby control devices which are set to cause toner dispensing whenrequired. Because of this vertical gravity feed in a hopper-typedispenser, there are occasions when toner becomes compacted and may notbe dispensed or replaced in the proper manner. In order to alleviatethis problem a toner dispenser has been devised wherein a roller meansis utilized to dispense the toner particles to the particular developingapparatus. This dispenser generally comprises a porous, flexible rollwrapped about a shaft. Although this dispensing unit has been founduseful for many purposes, certain problems have developed due to theundesirable manner in which the roll has been fixed to the shaft.Presently, a conventional glue comprising a hard protein substance,largely gelatin, is used to bond the dispenser roll to the shaft.However, this technique has been found ineffective in that it takes aconsiderable period of time for the glue to dry, and, in addition, thebond made between the dispenser roll and the shaft is poor and theuniformity of the seal inadequate. As the flexible cylinder is pulledonto the shaft the glue tends to collect further contributing to theinadequate seal.

Therefore, it is an object of this invention to provide a dispensingapparatus which will overcome the above noted disadvantages.

It is a further object of this invention to provide a means for securelyfixing a toner dispensing roll to the surface of a drive shaft.

It is still a further object of this invention to provide a novel tonerdispenser to be used in an electrophotographic apparatus.

It is yet still a further object of this invention to provide a novelmethod for preparing a toner dispenser roll for an electrophotographicimaging apparatus.

The foregoing objects and others are accomplished in accordance with thepresent invention, generally speaking, by utilizing a polymeric adhesiveto bond the dispenser roll to the drive shaft, thereby providing auniform and effective bond between the roll and the shaft. This isachieved in a very short period of time. A thin coating of a polymericadhesive is formed about the surface of the shaft. A porous, flexibleroll or sleeve such as polyurethane foam is fitted around the coated rodso as to form a continuous roller comprising the drive or support rod, apolyurethane roll about the rod and the intermediate adhesive layer. Theadhesive material is then heated to its melting temperature for a timesufficient to form the desired bond between the polyurethane and theunderlying support substrate. The roller configuration is then allowedto cool. The adhesive solidifies providing the necessary bond betweenthe urethane and the substrate for application in an electrophotographicimaging apparatus.

The invention is further described by the accompanying drawings wherein:

FIG. 1 represents a schematic sectional view of an electrostaticprinting apparatus embodying the toner dispenser of the presentinvention;

FIG. 2 is a partial sectional view of a toner dispensing mechanism foruse with the developing apparatus of an electrostatic imaging machine asset out in FIG. 1; and

FIG. 3 is a cross sectional view of the toner dispenser roll of thepresent invention.

For a general understanding of the electrostatic system in which theinvention may be incorporated reference is made to FIG. 1 in whichvarious components of an electrostatic system are schematicallyillustrated. As in all electrostatic systems such as a xerographicmachine of the type illustrated, a light image of an original 1 to bereproduced is projected onto the sensitized surface of a xerographicplate 12 to form an electrostatic latent image. Thereafter, the latentimage is developed with an oppositely charged developer materialcomprising toner particles to form a xerographic powder imagecorresponding to the latent image on the plate surface. The powder imageis then electrostatically transferred to a support surface such as paperto which it may be fixed by a fusing device whereby the powder image iscaused to permanently adhere to the support surface.

The electrostatic developer material commonly used comprises a pigmentedresinous powder referred to as toner and a carrier of large granularbeads removed in the triboelectric series from the toner so that atriboelectric charge is generated between the toner powder and thegranular carrier. The toner is attracted to the electrostatic latentimage from the carrier to produce a visible powder image on aninsulating surface.

In the illustrated apparatus, an original 1 to be copied is placed upona transparent support platen 2 arranged in an illumination assemblygenerally indicated by the reefrence numeral 10. While on the platen anillumination system flashes light rays upon the original producing imagerays corresponding to the informational areas of the original. The imagerays are projected by means of an optical system 11 to an exposurestation A for exposing the photosensitive surface herein represented asa xerographic or photoconductive belt 12. The photoconductive belt ischarged prior to reaching the exposure station by a corona device 13located at a belt run extending between support rollers 14 and 15. Theexposure station extends between the roller 14 and roller 16.

The exposure of the belt surface to the light image discharges thephotoconductive layer in the areas struck by light, thereby producing anelectrostatic latent image corresponding to the projected light image ofthe original. As the belt surface continues its movement theelectrostatic latent image passes through a developing station B locatedat a third run of the belt between rollers 16 and 15 at which there ispositioned a developing apparatus generally designated 17. Any suitablemeans (not shown) such as vacuum or tensioning means may be utilized formaintaining the belt fiat in all three belt runs and, in addition, thebelt run related to the development zone B is maintained at an inclinedplane. The developing apparatus 17 comprises a toner dispenser generallyindicated by reference numeral 18 which delivers the toner particles tothe developing zone B by way of the specific development means containedin housing 26. \As toner powder images are formed, additional tonerparticles are supplied to the chamber closed by housing 26 by the tonerdispenser 18.

The developed image is next transported by the belt to a transferstation C located at a point of tangency on the belt as it moves aroundthe roller 15. A sheet of copy paper is moved at a speed synchronousWith the moving belt in order to accomplish transfer of the developedimage. There is provided at the transfer station C a transfer roll 19which is arranged on the frame of the machine for contacting thenon-transfer side of each sheet of copy paper as the latter is broughtinto contact with the belt 12. The transfer roller 19 is electricallybiased by corona roller 20 with sufficient voltage so that a developedimage on the belt 12 may be electrostatically transferred to thetransfer sheet S as it is brought into contact therewith. A strippingfinger or air pufling device 21 is positioned to strip the sheet fromthe roller 19 and continues to remove the transfer sheet S by way ofvacuum conveying system 22 to final discharge at station 30.

There is also provided a suitable sheet transfer mechan1sm adapted totransport the sheets of paper from a paper handling mechanism generallyindicated by the reference numeral 23' to the transfer station C. A programming device operatively connected to the mechanism 23, stripperdevice 21 and the illumination system 11 is effective to present adeveloped image at the transfer station C in timed sequence with thearrival of a sheet of paper so that these elements function for theirintented purpose. After the sheet S supporting the transferred tonerimage 1s stripped from the belt 12 via roller 19 it is conveyed by theconveying system 22 into a fuser assembly generally indicated by thereference numeral 24 wherein the developed toner particles or powderimage on the transfer sheet are permanently aflixed thereto. Afterfusing, the finlshed copy is discharged from the apparatus at station30. The toner particles remaining as residue from the developed image,background particles and those particles not otherwise transferred, arecarried by the belt 12 to a cleaning apparatus 25 positioned on the runof the belt between rollers 14 and 15. The cleaning device comprises arotating brush, a Corotron for neutralizing charges remalnmg on theparticles and a discharge lamp for discharging any remainingelectrostatic charges on the belt. The run of the belt adjacent to thecleaning device is maintamed on an inclined plane relative to thehorizontal, as this run leaves the uppermost roller 15. Such anarrangement maintains the relatively straight line of copy sheetmovement which operatively cooperates with the printing belt 12 at itshighest point.

Referring now to FIG. 2, a sectional view of the developmg apparatus 17is represented comprising the toner dispenser housing 18 and thedeveloper housing 26. The housing 26 is substantially closed except foran opening adjacent the photoconductive belt 12 so that development ofthe latent image may be realized. This housing serves as a container forthe developer material and the specific development mechanism utilizedin the respective apparatus. In the present instance the developmentmechan1sm is represented as a magnetic development system comprisingfour magnetic brushes 31, 32, 33 and 34, a paddle wheel impeller 46,having a plurality of blades radially extending therefrom, and rotatablymounted within the chamber 26 by drive shaft 47. During a developmentcycle the impeller 46 is rotated in the direction shown by the arrow,transporting developer material to the lower surface of the magneticbrush 31. The depleted developer material which is carried beyond themagnetic brush 34 or the last brush in the chain of magnetic brushes isconveyed back into the housing 26 to be reused for development purposes,by a longitudinal plane or baffle plate 61 via a cross mixing baffie(not shown) which controls the movement of the development material intoworking engagement with the paddle wheel 46 for presenting thedevelopment material to the magnetic brush cylinders.

The developer apparatus 17 comprises a dispenser housing 18 havingmounted therein for rotation a developer dispenser 82 comprising adispenser roll 83 mounted on a shaft 84. The dispenser roll ispreferably formed of a porous flexible material such as polyurethanefoam, silicone foam, polyethylene foam and polystyrene foam. The porousnature of the dispenser roll provides isolated areas in which tonerparticles may be contained during the dispensing thereof. Tonerparticles 86 completely surround the dispenser roll, thereby allowingthe particles to become embedded in the surface thereof. The shaft 84for the roll 83 is arranged so that the inner edge 85 of partition plate81 extends slightly into the periphery of the roller. The periphery ofthis roller also similarly is engaged by the protruding edge 86 of anupturned portion of the lower wall of the housing 18. Upon rotation ofthe dispenser roll particles contained in the periphery thereof areflipped out by the action of the edges 85 and 86. The toner particles sodislodged are cascaded down to the developer mechanism of the developerapparatus.

Referring now to FIG. 3 theer is seen a cross section of the developerdispenser 90 of the present invention comprising the dispenser roll 91,a drive shaft 92 and the intermediate adhesive layer 93. The drive shaftmay be fabricated from any suitable material such as metal, as forexample aluminum and steel or plastic such as Teflon,polytetrafiuroethylene. Any suitable adhesive polymer may be used as theintermediate bonding layer of the present invention. Polymeric adhesiveare generally classified according to chemical composition and includethermoplastic adhesives, elastomeric adhesives, thermosetting adhesives,and alloy adhesives, the latter referring to adhesive compounds made upfrom resins of two or more of the previously chemical compounds, e.g.thermosetting and thermoplastic or thermosetting and elastomeric. Thethermoplastic adhesives can be softened or melted by heating andhardened by cooling. They are based on thermoplastic resins dissolved insolvent or emulsified in water. Elastomeric adhesives are based onnatural and synthetic rubbers, and are available as solvent dispersionsand latexes, or water dispersions. They are primarly used as compoundswhich have been modified with resins to form some of the adhesive alloysdiscussed above. They are similar to the thermoplastics in that theysoften with heat. Thermosetting adhesives are based on thermosettingresins that soften with heat only long enough for the cure to initiate.Once cured, they become relatively infusible up to their decompositiontemperature. The alloy type adhesive refers to adhesive compounds formedfrom resins of two or more different chemical families as stated above.In such adhesives the performance benefits of two or more types ofresins can be combined. For example, a thermosetting resin may beplasticized by a second resin resulting in improved toughness andflexibility. Typical thermoplastic adhesives include polyvinyl acetate,polyvinyl alcohol, aerylic esters, ethylene-vinyl acetate, cellulosenitrate, asphalt and oleo-resin adhesives. Typical thermosettingadhesives include phenolic, resorcinol, phenolresorcinol, epoxy,epoxy-phenolic, urea, melamine, and alkyd resins. Elastomeric adhesivesinclude natural rubber, reclaimed rubber, butadiene, neoprene,acrylonitrilebutadiene, and silicon. Alloy type, adhesives includephenolic-polyvinyl butyral, phenolic-polyvinyl formal, phenolic-neoprenerubber, phenolic-nitrile rubber and modified epoxy.

The process of preparing the dispenser member of the present inventionis preferably accomplished in reference to a sequential mode ofoperation wherein a thermoplastic or elastomeric type of adhesive isutilized. In this instance the adhesive is applied to the support rod,heated to its softening temperature and then cooled to produce theadhesively coated rod. Then the polyurethane or porous dispenser roll isformed about the coated rod, heat again applied to resoften the adhesiveand then the entire composite cooled to produce the final dispensingmember. Although this is a preferred mode of operation, the process ofpreparing the developer dispenser may be carrier out in a simultaneousmode of operation whereby the adhesive material and the porous dispenserroll are applied together in a layered configuration to the support rodand heat applied in a one step process. Cooling produces the dispensingmember in a one-heating-step process. In this particular embodiment thethermosetting adhesives or the alloy adhesives may be found useful inaddition to the thermoplastic and elastomeric adhesives. Thethermoplastic or elastomeric adhesive may be applied to the shaft by anysuitable technique such as preheating the adhesive material to itsmelting or softening temperature and rolling the rod in a metered mannerthrough the melted material, clip coating the adhesive onto the surfaceof the metal rod, brushing the adhesive material onto the rod, flowcoating the rod with the adhesive, or pre forming the polymeric adhesivein the form of a sleeve, slipping the sleeve over the rod and thenapplying heat either directly to the adhesive or indirectly by way ofthe rod,, when the latter is metal, in order to soften the material andestablished the necessary chemical bond between the rod and theadhesive. The thickness of the coating is not considered to be criticaland generally will be at least about 5 mils or greater. After thethermoplastic material or adhesive resolidifies, a sleeve or roll of theporous material, such as a polyurethane roll, may be placed over theshaft producing the composite developer dispenser set out in FIG. 3. Thepolymeric material is then reheated to its melting or softeningtemperature by any one of a number of techniques such as applyingelectric current through the shaft, applying direct heat to the shaft,when the shaft is metal, using a hollow red or cylinder and inserting aheating element such as a quartz heating element, induction or capacitorheating, or placing the entire configuration in an oven regulated to thesoftening or melting temperature of the particular adhesive. After thethermoplastic has been softened the heating environment is removed andthe dispenser allowed to cool, thus producing an excellent uniform bondof a porous roll to the shaft.

Although the above discussion in many instances was very specific interms of conditions and materials used, any of the above-listed typicalmaterials and alternate process steps may be implemented in order tocarry out the present invention. In addition to the steps used, as setout above, other steps or modifications may be implemented, ifdesirable. For example, the support rod may be surface treated in orderto enhance its response to the adhesive material. In addition, othermaterials may be incorporated in the porous dispenser roll, the adhesivepolymer, or the support member which will enhance, synergize orotherwise desirably eifect the system of the present invention. Forexample, silane adhesion promoters may be added to the adhesive toincrease its respective adhesive properties.

Those skilled in the art will have other modifications occur to thembased on the teachings of the present invention. These modifications areintended to be encompassed Within the scope of this invention.

What is claimed is:

1. A method of preparing a toner dispenser for use in an electrostaticprinting apparatus comprising applying a polymeric adhesive to thesurface of a plastic support rod, heating said rod to soften saidadhesive such that the adhesive flows in a uniform manner over thesurface of said rod so as to form a uniform coated layer thereon,cooling said uniformly coated rod, adapting about the surface of saidcoated rod a porous dispenser roll material selected from the groupconsisting of polyurethane, polyethylene, polystyrene and silicone,heating the configuration to resoften said polymeric adhesive, andcooling the configuration so as to bond said dispenser roll material tosaid support rod.

2. A method of preparing a toner dispenser according to claim 1 whereinsaid porous dispenser roll comprises polyurethane.

3. A method of preparing a toner dispenser according to claim 1 whereinsaid polymeric adhesive is selected from at least one member of thegroup consisting of thermoplastic adhesives, thermosetting adhesives,elastomeric adhesives, and alloy adhesives.

4. A method of preparing a toner dispenser according to claim 1 whereinsaid support rod is a metallic shaft.

5. A method of preparing a toner dispenser according to claim 1 whereinsaid support rod is a hollow metallic cylinder and said heating stepsare realized by the insertion of a heating element within the cavity ofsaid cylinder.

6. A method of preparing a toner dispenser according to claim 5 whereinsaid heating steps are carried out by applying an electric current tosaid metallic cylinder.

7. A method of preparing a toner dispenser for use in an electrostaticprinting apparatus comprising applying a polymeric adhesive to thesurface of a metallic support rod, heating said rod to soften saidadhesive such that the adhesive flows in a uniform manner over thesurface of said rod so as to form a uniform coated layer thereon,cooling said uniformly coated rod, adapting about the surface of saidcoated rod a porous dispenser roll material selected from the groupconsisting of polyurethane, polyethylene, polystyrene and silicone,heating the configuration to resoften said polymeric adhesive, andcooling the configuration so as to bond said dispenser roll material tosaid support rod.

8. A method of preparing a toner dispenser according to claim 7 whereinsaid heating steps are carried out by applying an electric current tosaid metallic support rod.

9. A method of preparing a toner dispenser for use in an electrostaticprinting apparatus comprising applying a thermoplastic adhesive to thesurface of a metallic or plastic drive shaft, heating said drive shaftto soften said adhesive such that the adhesive flows in a uniform mannerover the surface of said shaft 50 as to form a uni form coated layerthereon, cooling said uniformly coated shaft, adapting about the surfaceof said shaft a porous dispenser roll material selected from the groupconsisting of polyurethane, polyethylene, polystyrene and silicone,heating the configuration to resoften said adhesive, and cooling theconfiguration so as to bond said dispenser roll to said shaft.

10. A method of preparing a toner dispenser according to claim 9 whereinsaid heating steps are carried out by applying an electrical heatingsource to said shaft.

11. A method of preparing a toner dispenser according to claim 9 whereinsaid drive shaft is a hollow cylinder and said heating source is aquartz. heating element which is inserted into the cavity of saidcylinder during said heating steps to provide the necessary adhesivesoftening effect.

References Cited UNITED STATES PATENTS 2,440,725 5/1948 Munger 156-294 X3,239,403 3/1966 Williams et al. 156-275 3,645,817 2/1972 Walker et al156--293 X 3,340,224 9/1967 Sherman et a1. 156293 X 3,635,117 1/1972Nagao 156-293 X I. TRAVIS BROWN, Primary Examiner W. H. LOUIE, JR.,Assistant Examiner US. Cl. X.R. 156-293, 294, 309

